Finding the Fourth Proportional to 1,012.73, 1,518.66 and 428.00

Step by Step Solution

1. Step 1: Write the proportion equation
   1,012.73 : 1,518.66 = 428.00 : x
2. Step 2: Convert to fraction form
   1,012.73/1,518.66 = 428.00/x
3. Step 3: Cross multiply
   1,012.73x = 1,518.66 × 428.00
4. Step 4: Simplify right side
   1,012.73x = 649,978.89
5. Step 5: Solve for x
   x = 649,978.89/1,012.73
6. Step 6: Final answer
   x = 641.81